VU
Dusky Tetraka Crossleyia tenebrosa



Taxonomy

Taxonomic note
Crossleyia tenebrosa (del Hoyo and Collar 2016) was previously listed as Bernieria tenebrosa.

Taxonomic source(s)
del Hoyo, J., Collar, N.J., Christie, D.A., Elliott, A., Fishpool, L.D.C., Boesman, P. and Kirwan, G.M. 2016. HBW and BirdLife International Illustrated Checklist of the Birds of the World. Volume 2: Passerines. Lynx Edicions and BirdLife International, Barcelona, Spain and Cambridge, UK.
Dowsett, R. J.; Forbes-Watson, A. D. 1993. Checklist of birds of the Afrotropical and Malagasy regions. Tauraco Press, Li
Sibley, C. G.; Monroe, B. L. 1990. Distribution and taxonomy of birds of the world. Yale University Press, New Haven, USA.

IUCN Red list criteria met and history
Red List criteria met
Critically Endangered Endangered Vulnerable
- - B1ab(i,ii,iii,v)

Red List history
Year Category Criteria
2016 Vulnerable B1ab(i,ii,iii,v)
2012 Vulnerable B1ab(i,ii,iii,v)
2008 Vulnerable B1a+b(i,ii,iii,v)
2004 Vulnerable
2000 Vulnerable
1996 Endangered
1994 Endangered
1988 Threatened
Species attributes

Migratory status not a migrant Forest dependency High
Land mass type Land-mass type - shelf island
Average mass -
Extent of occurrence (EOO)

Estimate Data quality
Extent of Occurrence breeding/resident (km2) 16,000 medium
Number of locations -
Fragmentation -
Population and trend
Estimate Data quality Derivation Year of estimate
No. of mature individuals 1500-7000 poor estimated 2000
Population trend Decreasing medium suspected -
Decline (3 years/1 generation past) - - -
Decline (5 years/1 generation past) - - -
Decline (10 years/1 generation past) - - -
Decline (10 years/3 generation future) - - -
Decline (10 years/3 generation past and future) - - -
Number of subpopulations 2-100 - - -
Largest subpopulations - - -
Generation length (yrs) 3.6 - - -

Population justification: The population size is preliminarily estimated to fall into the band 2,500-9,999 individuals. This equates to 1,667-6,666 mature individuals, rounded here to 1,500-7,000 mature individuals.

Trend justification: The species's population is suspected to be declining in line with the clearance and degradation of lowland rainforest in eastern Madagascar. The likely rate of decline, however, has not been estimated.


Country/territory distribution
Country/Territory Occurrence status Presence Resident Breeding Non-breeding Passage
Madagascar N Extant Yes

Important Bird and Biodiversity Areas (IBA)
Country/Territory IBA Name
Madagascar Marojejy National Park
Madagascar Zahamena National Park and Strict Reserve

Habitats & altitude
Habitat (level 1) Habitat (level 2) Importance Occurrence
Forest Subtropical/Tropical Moist Lowland major resident
Altitude 200 - 950 m Occasional altitudinal limits  

Threats & impact
Threat (level 1) Threat (level 2) Impact and Stresses
Agriculture & aquaculture Annual & perennial non-timber crops Timing Scope Severity Impact
Ongoing Majority (50-90%) Slow, Significant Declines
Stresses
Ecosystem degradation, Ecosystem conversion
Biological resource use Logging & wood harvesting Timing Scope Severity Impact
Ongoing Minority (<50%) Slow, Significant Declines
Stresses
Ecosystem degradation, Ecosystem conversion

Recommended citation
BirdLife International (2019) Species factsheet: Crossleyia tenebrosa. Downloaded from http://www.birdlife.org on 19/03/2019. Recommended citation for factsheets for more than one species: BirdLife International (2019) IUCN Red List for birds. Downloaded from http://www.birdlife.org on 19/03/2019.